TW201819694A - Silicon ingot growth crucible with patterned protrusion structured layer - Google Patents

Abstract

A crucible for growing silicon ingots is proposed. The crucible comprises a vessel having a bottom wall and side walls surrounding an inner portion of the vessel. A coating layer is applied to inner surfaces of the bottom wall and the side walls, the coating layer comprising a temperature-resistant material compatible with ingot growth from molten silicon such as silicon nitride. Furthermore, a patterned protrusion layer is applied at the inner surface of the bottom wall. The patterned protrusion layer comprises a matrix consisting of a temperature-resistant material compatible with ingot growth from molten silicon such as silicon nitride. Furthermore, the patterned protrusion layer further comprises particles of a nucleation enhancing material such as silica, the particles locally protruding from the matrix. Accordingly, the protruding particles may generate a pattern of multiple nucleation points during crystal growth of the ingot. Due to such multiple nucleation points, a dislocation density defect propagation towards a top may be reduced during crystal growth such that e.g. solar cells produced with wafers sliced from the resulting ingot may have an improved conversion efficiency.

Description

Silicon ingot growth crucible with patterned protruding structure layer

FIELD OF THE INVENTION The present invention relates to a crucible for growing silicon crystal ingots, which can be used, for example, in the manufacture of polycrystalline silicon wafers for solar cell production. The invention also relates to a method for preparing a crucible.

Background of the invention

Solar cells are photovoltaic devices used to convert light energy into electrical energy. Solar cells are generally based on a semiconductor substrate. Most commercially available solar cells are manufactured using a silicon substrate (such as a silicon wafer).

Silicon wafers are generally made by slicing or sawing a wafer from a solid silicon block. The silicon block is typically made by melting purified silicon and then solidifying the melt. Depending on the physical conditions, the curing may result in a mono-crystalline silicon block or a multi-crystalline (mc-Si) or polycrystalline silicon block.

Polycrystalline silicon is, in most cases, filled or casted into a specific crucible by a liquid silicon melt, and then controlled by a specific The method is followed by cooling to solidify the melt. In general, physical conditions during the solidification process can significantly affect the physical characteristics of the crystalline silicon blocks formed. This crystalline silicon block is also called a silicon ingot.

Traditionally, the crucibles used to grow silicon ingots consisted of materials such as silica [also known as quartz crucible], graphite, silicon carbide or similar Made of highly heat resistant materials. In most cases, the surface of this container is coated with an additional layer to serve as, for example, barriers to prevent any contaminants from diffusing from the container into the extremely hot silicon melt. A coated layer is also provided to simplify a release of the ingot from the crucible after curing.

Summary of invention

There may still be a need for an improved crucible for growing silicon ingots, especially crucibles capable of generating ingots with better physical characteristics. In particular, there may still be a need for a crucible that has been improved and can be used to melt a silicon ingot and use the ingot as a basis to form a silicon wafer for high-performance solar cells. In addition, there may still be a need for a better method for preparing the crucible.

These requirements can be fulfilled using the crucible and the method under separate terms. Preferred embodiments will be defined in these subsidiary items and in this specification.

According to a first aspect of the present invention, a crucible for growing a silicon ingot is proposed. The crucible includes a container having a bottom wall and a side wall surrounding an interior of the container. The crucible also includes a coating layer that is applied to the bottom wall and the inner surface of the side wall. The coating layer contains a heat-resistant material that is compatible with ingots grown from molten silicon, such as, for example, silicon nitride. The crucible also includes a patterned protrusion layer that is applied to the inner surface of the bottom wall. The patterned protruding layer contains a matrix composed of a temperature-resistant material [such as, for example, silicon nitride] compatible with ingots grown from molten silicon. The patterned protruding layer also contains particles of a nucleation enhancing material, the particles partially protruding from the substrate of the patterned protruding layer.

According to a second aspect of the present invention, a method for preparing a crucible for growing a silicon ingot is proposed. The method includes at least the following steps, preferably in the specified order: first, a container is provided having a bottom wall and a side wall surrounding the interior of the container. Next, a coating layer is applied to the bottom wall and the inner surface of the side wall. This coating layer contains a heat-resistant material compatible with ingots grown from molten silicon, such as, for example, silicon nitride. A heat-resistant material should be able to withstand temperatures up to at least 1000 ° C, preferably at least 1400 ° C or even at least 1500 ° C, without significant damage or deterioration. Subsequently, a patterned protruding layer is applied to the inner surface of the bottom wall, that is, over the coating layer previously applied to the bottom wall. The patterned protruding layer contains a substrate composed of a heat-resistant material, such as silicon nitride, compatible with ingots grown from molten silicon. In addition, the patterned protruding layer contains particles of a nucleation promoting material. Wherein, the patterned protruding layer is applied in this manner, and the particles are adapted so that the particles locally protrude from the substrate.

The principles related to the embodiments of the present invention can be understood as the basis of the following ideas and cognitions, in particular and without limiting the scope of the present invention.

As pointed out in the introduction, it was discovered that a coated wall of a container containing a crucible of a heat-resistant material may be beneficial for a variety of reasons. In particular, the coating layer can prevent contaminants from diffusing from the container into a hot silicon melt that is cast into the crucible. In addition, the coating layer can be used as a release layer to simplify a demolding process of the cured silicon ingot from the crucible. For this purpose, the coating is typically made such as by forming a non-wetting agent when in contact with a liquid silicon melt. For example, a coating layer containing silicon nitride (eg, in the form of a silicon nitride powder) has been proven to provide good protection and releasing characteristics for the container of the crucible. Therefore, all the inner surfaces of the walls of the container (that is, the surfaces that point to the interior of the container and thus contact a hot silicon melt that is cast into the container) are preferably coated with the coating Floor.

However, it has been discovered that silicon ingots that are melt-cast in the coated containers described above may have a non-optimal characteristic when used to cut silicon wafers for silicon solar cell production. (non-optimal characteristics).

Surprisingly, it has now been discovered that providing an inner surface with a bottom wall of the container to which a patterned protruding layer is applied can affect the properties of the formed silicon ingot in a positive manner. That is, a solar cell made from a wafer cut from the silicon ingot can have an improved efficiency. In particular, it is assumed that the patterned protruding layer may be changed to a surface morphology [eg, to increase a roughness] of the inner surface of the container. In addition, the patterned protruding layer may cause local temperature non-uniformities when a vertical temperature gradient is high. Additionally, the patterned protruding layer may include randomly distributed nucleation promoting particles on the substrate, which may serve as wetting points, thereby changing or improving wetting characteristics to Help the silicon nucleate.

The coating layer can be deposited directly on one or more walls in the crucible. The patterned protruding layer can be directly deposited on the coating layer below it, that is, in direct mechanical contact with the coating layer. Alternatively, an additional layer with appropriate temperature-resistance may be inserted between the patterned protruding layer and the coating layer and / or between the coating layer and a wall of the crucible.

Specifically, the patterned protruding layer contains a substrate, which may be a heat-resistant material that is the same as or similar to the material of the coating layer below it.

In particular, the substrate may include or consist of silicon nitride. Similarly to the coating layer, the material of the substrate can be used as a releasing agent. In this context, a "heat-resistant material compatible with ingots grown from molten silicon" can be understood as a material that does not significantly and permanently change its physical and / or chemical properties when affected by temperature, although they This typically occurs during the growth of an ingot from a silicon melt, that is to say a temperature typically exceeding 1000 ° C or in many cases exceeding 1500 ° C. In particular, the heat-resistant material cannot be melted or burned at the aforementioned temperature. The substrate of the patterned protruding layer may form a layer or a film. Fine particles of a nucleation promoting material may be included in the substrate. Among them, the characteristics of the substrate and the particles are adapted so that the particles locally protrude from the substrate. In other words, for example, the thickness of an inner surface of a substrate layer applied to the bottom wall may be the same order of magnitude or may be smaller than at least a majority of the particles embedded in the substrate. So that at least the particles are not completely coated in the substrate and protrude from the substrate toward the interior of the container. In other words, the protruding particles form fine or even microscopic protrusions extending from the inner surface of the bottom wall toward the inside of the container. The highlights can form a regular or an irregular (eg random) pattern.

These protruding particles are made of a nucleation promoting material. This means that the particles are generally made of a material that is different from the material of the substrate and has other physical properties. Therefore, due to the different physical characteristics, each of the protruding particles can serve as a nucleation point when the silicon melt in the crucible is solidified. In other words, when the silicon melt in the crucible is cooled, the solidification process will preferably start at one of the nucleation points.

It has been observed that providing a large number of nucleation points when solidifying a silicon melt can generate fine crystal grains in the formed silicon ingot. The presence of the fine grains in the ingot can thus reduce a dislocation density defect propagation towards the top of the ingot. Therefore, the physical characteristics of the wafer cut from the ingot can be enhanced and the conversion efficiency of a solar cell produced using the ingot can be improved.

According to a specific example, the patterned protruding layer is applied only to the inner surface of the bottom wall.

In other words, although the patterned protruding layer is applied to the inner surface of the bottom wall, it is preferably not applied to the inner surface of the side wall of the container.

On the one hand, it has been observed that, in order to obtain the beneficial effect of the majority of nucleation points provided by the expected reduction of the difference in density of the differential row density, the patterned protruding layer is applied to the bottom wall only May be enough. The application of the patterned protruding layer to the side wall of the container also showed that the physical characteristics of an ingot grown in the crucible were not further improved. In another aspect, it was shown that applying the patterned protruding layer to the inner surface of the bottom wall but not to the inner surface of the side wall can improve the characteristics of the crucible during the growth of a silicon ingot . For example, the non-wet inner surface of the sidewall that is only covered by the coating layer but not covered by the patterned protruding layer may simplify a demolding process of a growing ingot after curing.

According to a specific example, the nucleation-promoting material is suitable for forming a wetting agent when in contact with a liquid silicon melt.

In other words, the material used for the particles contained in the patterned protruding layer should preferably be selected so that a liquid silicon melt in contact with the protruding particles located at the bottom of the crucible can be used. At least the particles protrude beyond the surface of the substrate to wet it. Due to this wetting characteristic, the particles can serve as nucleation points to change the surface configuration of the layer covering the inner surface of the bottom wall of the container.

According to a specific example, the particles of the nucleation-promoting material are silica sand (SiO ₂ ), silicon carbide (SiC), or carbon (Carbon, C) particles. Silica sand (SiO ₂ ) may be a better choice.

In other words, the particles may be composed of silicon oxide or silicon carbide or carbon and may have a typical size and shape like grains of sand. For example, the particles may have sharp points, sharp edges, or the like. Alternatively, the particles may be round or even sphere-like. This sand particle has been observed to act as a nucleation point when it partially protrudes from a substrate consisting essentially of silicon nitride and contacts the molten silicon to be solidified.

For example, the particles of the nucleation promoting material may have a size between 20 μm and 2 mm, preferably between 100 μm and 1 mm.

The size of the particles has been observed to produce a beneficial patterned protruding layer, especially when the particles can protrude slightly from a surrounding substrate, for example, to several micrometers to several hundred micrometers, but do not extend beyond Grow into the interior of the container, otherwise it may interfere with the growth of a silicon ingot or even damage a superficial layer of the growth ingot.

It should be understood that the particles contained in the patterned protruding layer may be provided by a particle size distribution. This means that substantially not all particles have the same size but the particle size can vary. Preferably, the particle size distribution is such that at least 50%, preferably at least 90% of all particles contained in the patterned protruding layer have a range falling between 20 μm to 2 mm or between 100 μm and Dimensions between 1 mm.

According to a specific example, the patterned protruding layer has a thickness between 0.3 mm and 3 mm, preferably between 1 mm and 2 mm.

Providing a patterned protrusion layer with this thickness has been observed to produce beneficial physical properties of ingots grown in this crucible.

It may be noted that the patterned protruding layer may not have a uniform thickness. For example, the patterned protruding layer may have a lower thickness in a region where only the substrate forms the patterned protruding layer, but it may have a lower thickness in a region where particles protrude from the substrate. Has an extended thickness. Therefore, the term "thickness of the patterned protruding layer" can be understood herein to mean an average thickness of the patterned protruding layer. In addition, since the thickness of the patterned protruding layer is mainly determined by the thickness used by the substrate to be applied over the inner surface of the bottom wall, the thickness of the patterned protruding layer roughly corresponds to The thickness of the substrate may exceed the thickness of the substrate layer by, for example, not more than 30%, preferably not more than 10%. In other words, the particles that partially protrude from the substrate can increase the average thickness of the patterned protruding layer to only about 30% of the thickness of the substrate layer, preferably only about 10%.

In particular, on the one hand, selecting a beneficial size distribution of particles contained in the patterned protruding layer, and on the other hand, selecting a beneficial thickness of the patterned protruding layer can affect A particle distribution in the patterned protruding layer and / or a distance that the particles protrude from the substrate of the patterned protruding layer.

For example, having large particles embedded in a very thin patterned protruding layer would generally cause only a few particles to protrude into the interior of the container, but the particles are relatively large and thus protrude quite well Far into this interior. This extreme configuration is not optimal for the physical characteristics of the resulting grown silicon ingot.

In the other extreme, the inclusion of very small particles in a thick patterned protruding layer may cause most of these particles to be completely encapsulated within the substrate rather than protrude from it. Therefore, only a few particles can be used as nucleation sites.

Therefore, on the one hand, the size distribution of the particles embedded in the substrate, and on the other hand, the thickness of the patterned protruding layer should be appropriately applicable in relation to each other.

Specifically, according to a specific example, a number of particles contained in the patterned protruding layer, a size distribution of the particles, and / or a thickness of the patterned protruding layer may be specifically selected. The particles of the nucleation promoting material protruding from the substrate are preferably contained in the patterned protruding layer with an area density between 1 / cm ² and 10 / cm ² . The ground is between 7 / cm ² and 10 / cm ² .

The particles in the patterned protruding layer providing this surface density have been observed to produce beneficial physical properties of silicon ingots grown in this crucible. In particular, the surface density of the protruding particles can affect a nucleation point density during curing of the ingot, and thus can affect a poor row defect density in the formed ingot in a beneficial manner. For example, a large number of nucleation points can increase the number of grains and in turn can generate more random grain boundaries per unit volume. The higher the grain boundary area per unit volume, the higher the probability of differential row insertion at the grain interface, because of misalignment between two adjacent grains. Due to energy barriers, it is not easy to tolerate the difference across the interface. Higher concentration differentials can be contained in a unit volume of material. As a result, more die interfaces will substantially slow a differential expansion.

The size distribution of silica sand or silicon carbide or carbon particles should be controlled as necessary to produce a stable slurry without any sedimentation and to avoid higher wafer level gaps Oxygen content (interstitial oxygen content). Smaller particles can result in higher surface area and more oxygen can be released into the melt during the ingot process. Most of these are typically lost from surfaces such as SiO gas self-melting, but a remaining portion may remain in the melt and may dissolve into crystalline silicon. Therefore, it may be beneficial to control particle size and / or particle size distribution.

According to a specific example, the coating layer has a thickness between 0.1 mm and 1 mm, preferably between 0.4 mm and 0.5 mm.

A coating layer having such a thickness can be easily applied to the inner surface of the container on the one hand, and at the same time, can provide sufficient protection and / or release characteristics.

According to a specific example, the coating layer is applied using a specific slurry (referred to herein as a “first slurry”), which includes at least a silicon nitride powder. In addition, in a preferred embodiment, the first slurry further includes a binding agent, a dispersing agent, and deionised water. Preferably, the first slurry does not contain any further ingredients or agents.

According to another specific example, the patterned protruding layer is applied using a second slurry containing at least silicon nitride powder and particles of a nucleation promoting material. In addition, according to a preferred embodiment, the second slurry further includes a binder, a dispersant, and deionized water. Again, preferably, the second slurry does not contain any further ingredients or reagents.

These first and / or second slurries can be easily added to the inner surface of the wall of the container. In addition, these slurries can be applied with a small amount of force and / or at a low cost. For example, the slurries may be sprayed on the inner surfaces. For example, a special dispensing spray system may be applied to spray the slurry onto surfaces to be covered by a coating layer and / or a patterned protruding layer, respectively. The coating of such internal surfaces can be completed at elevated temperatures. Or other techniques of applying the first and / or second slurry can be used. For example, a patterned mask [as it is commonly used in, for example, screen printing] can be applied.

The nitrided fine powder contained in the slurry may be a small silicon nitride particle having a typical size ranging from 0.1 μm to 5 μm. The silicon nitride powder may have a purity of more than 98%, more preferably more than 99.9%.

The adhesive may include polyvinyl alcohol or colloidal silica. Preferably, the adhesive may include colloidal silica and about 50% by weight solid silica having a particle size of 5-100 nanometers.

The dispersant may include propylene glycol.

It should be noted that the statement that "a layer is applied using a specific slurry" can be interpreted on one hand as defining a specific characteristic of the production process used to form the respective layer, or on another On the one hand, it may be a feature that defines the structure of the individual layers formed by the particular production method. To put it more clearly, a coating layer applied using a first paste or a patterned protruding layer applied using a second paste will have roughly these layers using a paste The physical and / or structural properties resulting from the fact that materials are applied are different from using other techniques {such as CVD [Chemical Vapour Deposition] or PVD [Physical Vapour Deposition]] Applied layer. For example, a coating layer or a patterned protruding layer that is applied using a specific slurry has a result of the fact that the slurry contains more or less macroscopic powder particles. A specific granular structure, however, a layer that is applied, for example, using CVD or PVD is typically more homogeneous, because it is based on smaller microscopic particles [such as atoms, molecules And / or their clusters] are built-up. In addition, although certain ingredients (such as the binder, the dispersant, and / or the deionized water) contained in the slurry during its processing may have disappeared during subsequent processing of the slurry and may thus Not present in the final coating layer and / or patterned protruding layer, the fact that these ingredients or reagents are part of the first and / or the second paste still typically results in the specificity of the layer formed Physical and / or structural characteristics. For example, the layers formed may have a typical porosity or morphology, which is a layer different from that applied using other technologies such as CDV or PVD, especially silicon nitride Floor.

According to a specific example of the method as defined in the second aspect of the present invention, compared to the second paste used to deposit the patterned protruding layer, the method for applying the coating layer is The first slurry has a lower viscosity.

For example, the first slurry may have a viscosity of less than 100 cP, preferably less than 10 cP, while the second slurry may have a viscosity of more than 100 cP, preferably more than 500 cP. . Due to its low viscosity, the first slurry can be easily applied with a uniform thickness. The higher viscosity second slurry may be sprayed or cast and then optionally dispersed on the inner surface of the bottom wall of the container.

The patterned plurality of protrusion spots or layers can be applied, for example, with the aid of a mask, such as screen printing, or through a special dispensing spray system. Therefore, a surface may have a surface structure of hills (wet) and valleys (non-wet).

According to a specific example, the first slurry has a lower density than the second slurry.

For example, the first slurry may have a density of less than 1.6 g / cm ³ , preferably less than 1.4 g / cm ³ , and the second slurry may have a density of more than 1.6 g / cm ³ , A density greater than 1.9 g / cm ³ is preferred.

The first slurry can be made with a lower solid content to avoid problems such as clogging or blocking in an automatic spray process. The second paste can be made with a higher solids content, for example, to produce a stable paste without any deposits and capable of printing out protruding points.

It should be noted that the possible features and / or benefits of the specific examples of the present invention are described herein in part in relation to a crucible and in part in relation to a method for preparing a crucible. Those skilled in the art will understand that according to the present invention, the features described for the specific example of the crucible can be similarly applied to a specific example of the method, and vice versa. In addition, those skilled in the art will understand that the characteristics of different specific examples may be combined or replaced with the characteristics of other specific examples and / or modified to achieve more specific examples of the present invention.

Detailed description of preferred specific examples

FIG. 1 shows a cross section of a crucible 1 according to a specific example of the present invention. The crucible 1 has a square shape, that is, it has a box shape or a cubic shape. Other geometries are possible for the crucible.

The crucible 1 includes a pot-like container 3 having a bottom wall 5 and a side wall 7. The bottom wall 5 is substantially rectangular and horizontal, and the side wall 7 is rectangular and substantially vertical. The bottom wall 5 and the side wall 7 can form an integral component forming the entire container 3. Alternatively, the bottom wall 5 and the side wall 7 may be separate components and may be installed together to form the entire container 3. The walls 5, 7 can be formed using sheet-like components. For example, the walls 5, 7 can be made using a fused silica sheet. Typically, the bottom wall 5 is tens of centimeters long and tens of centimeters wide. The side wall 7 is typically tens of centimeters high and tens of centimeters wide. The bottom wall 5 and the side wall 7 typically have a thickness ranging from several millimeters to several centimeters, such as between 3 mm and 10 cm.

The bottom wall 5 and the side wall 7 surround an interior 9 of the container 3. Among them, the container 3 is preferably opened at the top.

A thin coating layer 11 is applied to the inner surfaces of the bottom wall 5 and the side wall 7. The coating layer 11 includes or consists of silicon nitride as a temperature-resistant material. The coating layer 11 can therefore withstand a very high temperature of the silicon melt cast into the container 3. Preferably, the coating layer 11 has a thickness of 400 μm to 500 μm. Preferably, the coating layer 11 is substantially homogeneous, that is, it does not contain particles visible to the naked eye other than the silicon nitride powder particles used to form the coating layer 11. In particular, the coating layer 11 may have a thickness uniformly visible to the naked eye, and may have a smooth, preferably flat surface that is visible to the naked eye. The part of the coating layer 11 covering the side wall 7 of the container 3 is preferably not covered by any other layer, that is, it is exposed towards the interior 9 of the container 3.

On the bottom wall 5, an additional layer is applied on the coating layer 11. This additional layer is a patterned protruding layer 13 which preferably covers the entire inner surface of the bottom wall 5. Therefore, on the bottom wall 5, the coating layer 11 is not exposed, but is covered by the patterned protruding layer 13 which is superimposed.

As can be seen in the enlarged view of FIG. 1, the patterned protruding layer 13 contains a matrix 15 in which a plurality of particles 17 are embedded. The substrate 15 contains silicon nitride as a heat-resistant material. The particles 17 are composed of a nucleation enhancing material, such as silica. The particles 17 protrude beyond the exposed surface of the upper portion of the substrate 15. Therefore, the protruding particles 17 form a pattern with nucleation enhancing tips protruding toward the interior 9 of the container 3.

The silicon oxide particles 17 may have a typical size ranging from 100 μm to 1 mm. A pattern size, that is, a lateral average distance between adjacent protruding particles 17, may fall within a typical range of 1 mm to 2 mm. A protruding height of the particles 17 may fall within a range of 1 mm to 2 mm.

Finally, the steps of a method for preparing or constructing a crucible 1 are described with an illustrative specific example.

To prepare or build the crucible 1, first, a container 3 having a bottom wall 5 and a side wall 7 is provided.

Next, a first silicon nitride coating slurry can be prepared by mixing a high-purity silicon nitride powder, deionized water, a binder, and a dispersant. The first slurry may then be sprayed or otherwise deposited on the inner surface of the bottom wall 5 and the side wall 7 of the square fused silicon crucible 1, for example by spraying or other methods such as screen printing. The first paste can be applied with a desired specific coating thickness, for example, between 400 μm and 500 μm. The coating is typically performed at an elevated coating temperature between 40 ° C and 50 ° C.

After the coating layer 11 has been applied through this method, a second slurry is prepared with silicon nitride powder, deionized water, a binder, and a wetting agent. The wetting agent can be formed by particles 17 made of a nucleation promoting material such as silica sand particles. Preferably, the second slurry is applied only to the inner wall of the bottom wall 5 or the coating layer 11 previously applied thereto.

When the first slurry has a relatively low density such as 1.37 g / cm ³ and a low viscosity such as 2.96 cP, the second slurry has a relatively high density such as 1.96 g / cm ³ Density and a high viscosity of about 700 cP.

After the coating layer 11 and the patterned protruding layer 13 have been applied to the inner surfaces of the walls 5 and 7 of the container 3, the coated crucible 1 is exposed to high temperature and open atmosphere (open atmosphere). ). Under these conditions, the first and second pastes are cured and form a uniform dense coating layer 11 and a patterned protruding layer 13, respectively.

The silicon ingots grown using this crucible 1 can show reduced differential density defects. In view of this, a solar cell made from a silicon wafer cut from the ingot can have improved conversion efficiency.

Finally, it should be noted that terms such as "comprising" do not exclude other elements or steps, and "an (a)" or "an" does not exclude a plural. Elements described in connection with different specific examples may also be combined.

1‧‧‧ Crucible

3‧‧‧ container

5‧‧‧ bottom wall

7‧‧‧ sidewall

9‧‧‧ Internal

11‧‧‧ Coating

13‧‧‧ patterned protruding layer

15‧‧‧ substrate

17‧‧‧ particles

In the following, specific examples of the present invention will be described herein in relation to additional drawings. However, neither the illustration nor the description should be interpreted as a limitation on the present invention.

FIG. 1 shows a cross-sectional view of a crucible according to a specific example of the present invention.

The figure is only a rough representation, not actual scale.

Claims (15)

A crucible for growing a silicon ingot, the crucible comprising: a container having a bottom wall and an inner side wall surrounding the container; a coating layer applied to the bottom wall and an inner surface of the side wall The coating layer contains a heat-resistant material that is compatible with ingots grown from molten silicon; a patterned protruding layer is applied to the inner surface of the bottom wall, and the patterned protruding layer contains A substrate composed of a heat-resistant material compatible with ingots grown from molten silicon, and further containing particles of a nucleation promoting material, the particles partially protruding from the substrate. As in the crucible of claim 1, wherein the patterned protruding layer is uniquely applied to the inner surface of the bottom wall. The crucible according to any one of claims 1 to 2, wherein the nucleation promoting material is suitable for forming a wetting agent when in contact with a liquid silicon melt. The requested item 1 to 3 according to any one of the crucible, wherein the nucleation promoting material into granules is silica sand (SiO ₂₎ particles, silicon carbide (SiC) particles and carbon (C) in which particles of a person. The crucible according to any one of claims 1 to 4, wherein the particles of the nucleation promoting material have a size between 20 μm and 2 mm, preferably between 100 μm and 1 mm. The crucible according to any one of claims 1 to 5, wherein the patterned protruding layer has a thickness between 0.3 mm and 3 mm, preferably between 1 mm and 2 mm. The crucible according to any one of claims 1 to 6, wherein particles of the nucleation promoting material protruding from the substrate are contained in the warp at a surface density of 1 cm ^-2 to 10 cm ^-2 . In the patterned protruding layer, it is preferably between 7 cm ^-2 and 10 cm ^-2 . The crucible according to any one of claims 1 to 7, wherein the coating layer has a thickness between 0.1 mm and 1 mm, preferably between 0.4 mm and 0.5 mm. The crucible according to any one of claims 1 to 8, wherein the heat-resistant material contained in at least one of the coating layer and the patterned protruding layer is silicon nitride. The crucible according to any one of claims 1 to 9, wherein the coating layer is applied using a first slurry containing silicon nitride powder, and preferably, the first slurry further contains a A binder, a dispersant, and deionized water. The crucible according to any one of claims 1 to 10, wherein the patterned protruding layer is applied using a second slurry containing silicon nitride powder and particles of the nucleation promoting material, and is Preferably, the second slurry further contains a binder, a dispersant, and deionized water. A method for preparing a crucible for growing a silicon ingot, the method comprising: providing a container having a bottom wall and an inner side wall surrounding the container; applying a coating layer to the bottom wall and the side wall The inner surface, the coating layer contains a heat-resistant material compatible with the ingot grown from the molten silicon; a patterned protruding layer is applied to the inner surface of the bottom wall, the patterned protruding layer contains A substrate composed of a heat-resistant material compatible with ingots grown from molten silicon, and further containing particles of a nucleation promoting material, wherein the patterned protruding layer is applied in this manner, and The particles are suitable for causing the particles to partially protrude from the substrate. The method according to claim 12, wherein the coating layer is applied using a first slurry containing silicon nitride powder, and the patterned protruding layer is using a silicon nitride powder and the forming layer. A second slurry of particles of the core promoting material is applied. The method according to any one of claims 12 and 13, wherein the first slurry has a lower viscosity than the second slurry. The method according to any one of claims 12 to 14, wherein the first slurry has a lower density than the second slurry.